JPH0637483B2 - Schiff base compound - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides a novel Schiff base compound useful as a raw material for producing a herbicide.

(Prior Art and Problems to be Solved by the Invention) The present inventors have conducted synthesis of N-substituted-haloacetamide using a Schiff base compound as a raw material and research on its physiological activity. As a result, they have found that the specific N-substituted-chloroacetamide has excellent herbicidal activity.

Conventionally, many Schiff base compounds as raw materials have been synthesized, and a method of reacting an amine compound with an aldehyde compound or a ketone compound is general.

However, when the Schiff base is synthesized by the synthetic method, the starting amine compound is limited to a general one. That is, as shown in general formula (II) (R ', R ", and R represent the same or different hydrogen atom, alkyl group, or aryl group.) Substituted vinylamine is generally unstable, and it is difficult to use the compound as a raw material for the Schiff base. Therefore, a Schiff base compound in which a substituted ethenyl group is directly bonded to a nitrogen atom has not been reported yet, and therefore, the herbicidal activity of N-substituted-haloacetamide using the Schiff base compound as a raw material has not been known at all.

(Means for Solving Problems and Curing) The inventors of the present invention have earnestly studied the synthesis of N-substituted-haloacetamide excellent in selective herbicidal activity that kills only weeds. As a result, they found that when a specific Schiff base compound was used as a raw material, an N-substituted-haloacetamide excellent in selective herbicidal activity was obtained, and completed the present invention.

That is, the present invention has the general formula (In the formula, R ₁ represents a substituted or unsubstituted heteroaryl group, R ₂ and R ₃ represent the same or different hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ₂ and R ₃ And may be linked to each other to form a cyclic alkylene group, R ₄ is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, or a substituted or unsubstituted aryl. R ₅ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X represents an oxygen atom or a sulfur atom, and n represents 0 or 1, provided that R ₅ is a hydrogen atom. n is 0.) is a Schiff base compound.

In the above general formula (I), R ₁ is a substituted or unsubstituted heteroaryl group. The unsubstituted heteroaryl group includes a heteroaryl group containing an oxygen atom, a sulfur atom, and a nitrogen atom, for example, a furyl group, a cenyl group, a pyrrolyl group, a benzofuryl group, a benzocenyl group, a pyrazolyl group, an imidazolyl group and a thiazolyl group. It is suitable.

The heteroaryl group may be substituted, and the substituent is not particularly limited, and a known substitutable group can be adopted. A specific example is as follows. That is, the number of carbon atoms is 1 to
6 alkyl group; halogen atom of chlorine atom, bromine atom, iodine and fluorine atom; alkoxy group having 1 to 6 carbon atoms; haloalkyl group having 1 to 6 carbon atoms; 1 carbon atom
An alkylthio group having 6 to 6; an alkyl group having 1 to 6 carbon atoms and / or a phenoxy group substituted or unsubstituted with a halogen atom selected from the group consisting of chlorine atom, bromine atom, iodine atom and fluorine atom; 1 carbon atom
To alkyl groups and / or phenyl groups substituted or unsubstituted with a halogen atom selected from the group consisting of chlorine atom, bromine atom, iodine atom and fluorine atom.

The most preferable examples of the above substituted heteroaryl group are as follows. That is, methylfuryl, dimethylfuryl, ethylfuryl, propylfuryl,
Chlorofuryl, bromofuryl, methoxyfuryl, ethoxyfuryl, propoxyfuryl, (trifluoromethyl)
Substituted furyl groups such as furyl, methylthiofuryl, ethylthiofuryl, phenoxyfuryl, and phenylfuryl; methylthienyl, dimethylthienyl, ethylthienyl, propylthienyl, butylthienyl, fluorothienyl,
Chlorothienyl, bromothienyl, methoxythienyl,
Substituted thienyl groups such as ethoxythienyl, propoxythienyl, (chlorothienyl) thienyl, (trifluoromethyl) thienyl, methylthiothienyl, ethylthiothienyl, dibromothienyl, dimethoxythienyl, phenoxythienyl, and phenylthienyl; N-methylpyrrolyl, N- Substituted pyrrolyl groups such as ethylpyrrolyl, methyl-N-methylpyrrolyl, chloro-N-ethylpyrrolyl, methoxy-N-methylpyrrolyl, methylthio-N-methylpyrrolyl, and phenoxy-N-methylpyrrolyl; methylbenzofuryl, chlorobenzofuryl, ethoxybenzofuryl, Substituted benzofuryl groups such as (trifluoromethyl) benzofuryl and phenoxybenzofuryl; ethylbenzothienyl, fluorobenzothienyl, methoxybenzothienyl, Substituted benzothienyl groups such as a fine phenyl benzothienyl; methyl pyrazolyl group, dimethyl-pyrazolyl group, a phenyl pyrazolyl group, a methoxy imidazolylmethyl group, and a phenyl imidazolylmethyl group, and methylthiazolyl group.

R ₂ and R ₃ in the general formula (I) are the same or different hydrogen atoms and alkyl groups having 1 to 6 carbon atoms, and R ₂ and R ₃ are linked to each other to form a cyclic alkylene. A group may be formed. The alkyl group may be a linear or branched alkyl group, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group,
Examples thereof include n-butyl group, iso-butyl group, n-pentyl group, and n-hexyl group. When R ₂ and R ₃ are linked to each other to form a cyclic alkylene group, the alkylene group is an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group. , And an octamethylene group are suitable.

R ₄ represented by the general formula (I) is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, or a substituted or unsubstituted aryl group. As the unsubstituted alkyl group, those specifically exemplified by R ₂ and R ₃ are preferable, and in addition to these, for example, an alkyl group having 7 or 8 carbon atoms such as a heptyl group and an octyl group is preferable. is there. Further, the alkyl group may be substituted,
The substituent is not particularly limited, but examples of industrially suitable ones are as follows. That is, the number of carbon atoms is 1
An alkoxy group having 1 to 6 carbon atoms; an alkylthio group having 1 to 6 carbon atoms; an alkylcarbonyl group having 1 to 6 carbon atoms; an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. A phenoxy group substituted or unsubstituted; an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group substituted or unsubstituted with a halogen atom. Specific examples of suitable substituted alkyl groups are as follows. For example, methoxymethyl, methoxyethyl, methoxypropyl, ethoxymethyl, ethoxyethyl, ethoxypropyl, ethoxypentyl, propoxymethyl, propoxyethyl, propoxybutyl, butoxyethyl,
Alkoxyalkyl groups such as butoxypropyl and pentoxyethyl; methylthiomethyl, methylthioethyl,
Alkylthioalkyl groups such as methylthiopropyl, methylthiobutyl, methylthiopentyl, ethylthioethyl, propylthiomethyl, propylthiopropyl, and butylthiomethyl; methylcarbonylmethyl, methylcarbonylethyl, methylcarbonylpropyl, methylcarbonylbutyl, methylcarbonylpentyl. , Alkylcarbonylalkyl groups such as methylcarbonylhexyl, ethylcarbonylethyl, ethylcarbonylpropyl, ethylcarbonylhexyl, propylcarbonylmethyl, propylcarbonylpropyl, butylcarboylethyl, pentylcarbonylpropyl, and hexylcarbonylbutyl; phenoxymethyl, phenoxyethyl , Phenoxypropyl, phenoxybutyl, (methylphenoxy) ethyl, (d Ruphenoxy) methyl, (propylphenoxy) ethyl, (methoxyphenoxy) propyl, (ethoxyphenoxy) butyl, (propoxyphenoxy) ethyl, (chlorophenoxy) methyl, (bromophenoxy) ethyl, (fluorophenoxy) propyl, and [( A phenoxyalkyl group such as chloro) methylphenoxy] ethyl; phenylmethyl, phenylethyl, phenylpropyl, (methylphenyl) ethyl,
Examples thereof include phenylalkyl groups such as (ethylphenyl) propyl, (propylphenyl) methyl, (methoxyphenyl) methyl, (methoxyphenyl) propyl, (ethoxyphenyl) ethyl, and (propoxyphenyl) ethyl.

Among the substituted or unsubstituted aryl groups represented by R _4, the unsubstituted aryl group is preferably a phenyl group, a naphthyl group, an anthranyl group, a phenanthrenyl group, or the like.

Further, the above-mentioned arena group may be substituted, and the substituent is not particularly limited, and a known substitutable group can be adopted. A specific example is as follows. That is, 1 to 6 carbon atoms
Alkyl group; chlorine atom, bromine atom, halogen atom of iodine and fluorine atom; alkoxy group having 1 to 6 carbon atoms; haloalkyl group having 1 to 6 carbon atoms; alkylthio group having 1 to 6 carbon atoms; carbon An alkyl group having 1 to 6 atoms and / or a phenoxy group substituted or unsubstituted with a halogen atom selected from the group consisting of chlorine atom, bromine atom, iodine atom and fluorine atom; from 1 to 6 carbon atoms And an alkyl group and / or a phenyl group substituted or unsubstituted with a halogen atom selected from the group consisting of chlorine atom, bromine atom, iodine atom and fluorine atom.

The most preferable examples of the substituted aryl group are as follows. That is, an alkylphenyl group such as methylphenyl, dimethylphenyl, ethylphenyl, dimethylphenyl, propylphenyl, butylphenyl, pentylphenyl, methylethylphenyl, and methylpropylphenyl; fluorophenyl, difluorophenyl, chlorophenyl, dichlorophenyl, trichlorophenyl, Halophenyl groups such as bromophenyl and iodophenyl; alkoxyphenyl groups such as methoxyphenyl, dimethoxyphenyl, ethoxyphenyl, propoxyphenyl, and butoxyphenyl;
(Haloalkyl) phenyl groups such as (chloromethyl) phenyl, (chloroethyl) phenyl, (chloropropyl) phenyl, (bromoethyl) phenyl, (fluoroethyl) phenyl, and (trifluoromethyl) phenyl; methylthiophenyl, ethylthiophenyl, And an alkylthiophenyl group such as propylthiophenyl; phenoxyphenyl, (methylphenoxy) phenyl, (ethylphenoxy) phenyl, (chlorophenoxy) phenyl, (bromophenoxy) phenyl, (fluorophenoxy) phenyl, and [chloro (methyl) phenoxy A phenoxyphenyl group such as phenyl; (methylphenyl) phenyl, (ethylphenyl) phenyl, (propylphenyl) phenyl, (chlorophenyl) phenyl, and (fluorophenyl) ) Phenylphenyl groups such as phenyl; substituted phenyl groups such as chloro (methyl) phenyl, chloro (ethoxy) phenyl, and methyl (methoxy) phenyl; methylnaphthyl, dimethylnaphthyl, ethylnaphthyl, chloronaphthyl, bromonaphthyl, dichloronaphthyl, Substituted arena groups include methoxynaphthyl, (trifluoromethyl) naphthyl, methylthionaphthyl, phenoxynaphthyl, phenylnaphthyl, methylanthranyl, chloroanthranyl, methoxyanthranyl, and methylphenanthryl.

R ₅ represented by the general formula (I) is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. The alkyl group is the above R
_The same groups as the alkyl groups of ₂ and R ₃ are preferred.

In the general formula (I), X is an oxygen atom or a sulfur atom. Further, n is 0 or 1. However, when R ₅ is a hydrogen atom, n is 0.

In many cases, the compounds having the groups specifically exemplified above have various positional isomers, but the compounds are not particularly limited and can be used in the present invention.

The structure of the compound represented by the general formula (I) of the present invention is
It can be confirmed by the following means.

(A) By measuring the infrared absorption spectrum (ir),
0cm ^-1 ~2800cm ^-1 near the based on CH bond absorption, 1630 cm ^-1
In the vicinity It is possible to observe strong absorption and the like.

(B) Each peak observed by measuring the mass spectrum (mS)
(Generally, m that is obtained by dividing ion molecular weight m by ion mass number e
Calculate the composition formula corresponding to the mass number represented by / e)
Therefore, the molecular weight of the compound used for measurement and the molecule
It is possible to know the bonding mode of each atomic group within. Immediately
Then, the sample used for the measurementIn general, the molecular ion peak (hereinafter M When
(Abbreviated) is observed and the molecular weight of the compound used for measurement is
You can decide. Further, the book represented by the above general formula
For compounds of the invention, M -(X)_nR₅Equivalent to
Characteristic peaks are observed and the binding pattern in the molecule is known.
You can

By measuring the (c) ¹ H- nuclear magnetic resonance spectra ^{(1 H-nmr),} it is possible to know the coupling state of the hydrogen atoms present in the compounds of the present invention represented by the general formula.
As a typical example of ¹ H-nmr [based on tetramethylsilane, δ (ppm)] of the compound represented by the general formula (I), the analysis results of the following compounds are shown below.

That is, a triplet of three protons based on a methyl group (f) at 1.32 ppm, a doublet of six protons based on a methyl group (c) at 1.85 ppm, and a methylene group (e) at 4.18 ppm. Proton 2
Quadruples, a doublet for one proton based on the thiophene ring (a) at 6.15ppm, a doublet for one proton based on the thiophene ring (b) at 6.40ppm, and methine at 7.23ppm. Group (d)
A singlet for one proton based on was observed.

(D) Oxygen is obtained by calculating the weight% of carbon, hydrogen, nitrogen, and halogen (or sulfur when sulfur is included) by elemental analysis, and subtracting the total weight% of the recognized elements from 100. You can calculate the weight% of
Therefore, the composition formula of the compound can be determined.

The Schiff base compound of the present invention includes R ₁ and R in the above general formula.
_The properties are slightly different depending on the types of ₂ , R ₃ , R ₄ , R ₅ , X, and n, and the degree of purification, but they are generally colorless to yellow liquids or solids at room temperature and atmospheric pressure. The compound of the present invention is soluble in general organic solvents such as benzene, ether, alcohol, chloroform, acetonitrile, dimethylformamide and dimethylsulfoxide, but it is sparingly soluble in water.

The production method of the compound represented by the general formula (I) of the present invention is not particularly limited, and a representative production method will be described as follows.

General formula (In the formula, R ₁ , R ₂ , and R ₃ are the same as defined above, and A
Is a hydrogen atom or a (trialkyl) silyl group. ] The imine compound shown by (In the formula, R ₄ , R ₅ , X, and n are the same as above,
Y and Z are hydrogen atoms or alkyl groups. However, n
If is 0, Part It may be. ) The compound represented by the above general formula (I) can be obtained by reacting with the compound represented by

The imine compound represented by the general formula (III), which is a raw material for the method, may be obtained by any method. In the general formula, it can be obtained by reacting a nitrile compound with an organomagnesium compound or an organolithium compound as shown in the following formula.

(In the formula, R ₁ , R ₂ , R ₃ , and A are the same as described above, and Q is Li or MgCl, MgBr, MgI.) The molar ratios of the two compounds charged in the reaction are appropriately selected as necessary. It may be determined, but usually equimolar or general formula (I
It is common to use the compound of V) in a slight excess.
The order of addition of both compounds is not particularly limited.

The reaction can be carried out in an organic solvent or without solvent. If a suitable one is used when an organic solvent is used,
Examples thereof include benzene, toluene, xylene, hexane, chloroform, methylene chloride, ethyl ether, dioxane, tetrahydrofuran, acetone, methyl ethyl ketone, acetonitrile, ethyl acetate, N, N-dimethylformamide, hexamethylphosphoramide, and dimethyl sulfoxide.

The reaction temperature in the above reaction can be selected from a wide range, and is generally -50 ° C to 200 ° C, preferably -30 ° C to 15 ° C.
It may be selected in the range of 0 ° C. The reaction time may vary depending on the raw materials and the reaction temperature, but it is usually 5 minutes to 10 days, preferably 30 minutes to 2 days. Further, it is preferable to carry out stirring during the reaction.

In order to accelerate the reaction, hydrochloric acid, acetic acid, p
Means for adding an acid such as toluenesulfonic acid, BF ₃ .Et ₂ O, a Lewis acid such as aluminum chloride, calcium hydride, molecular sieves, silica gel, alumina or the like is often suitably used.

The method for isolating and purifying the target purified product, that is, the Schiff base compound represented by the general formula (I) is not particularly limited, and a known method can be adopted. For example, the target product can be obtained by distilling the reaction solvent from the reaction solution and then vacuum distilling the residue. When the reaction is carried out without a solvent, the desired product can be obtained by vacuum distillation of the reaction solution. Further, purification by chromatography, or purification by recrystallization when the product is a solid, can be adopted.

The Schiff base compound represented by the general formula (I) of the present invention is a compound useful as a raw material for herbicides having excellent selective herbicidal activity.

For example, by reacting with a Schiff base compound of the present invention, trichlorosilane or dichlorosilane, and chloroacetyl chloride, a compound of the general formula It can be obtained chloroacetamide - _{(wherein, R 1, R 2, R} 3, R 4, R 5, X, and n are as defined above.) N-substituted represented by.

When the N-substituted-chloroacetamide is obtained from the Schiff base of the present invention, the reaction can be carried out without a solvent, but it is generally preferred to carry out the reaction in a solvent. The solvent can be used without limitation as long as it is an inert organic solvent that does not interact with coexisting raw materials such as trichlorosilane or dichlorosilane and chloroacetyl chloride. Generally, benzene, toluene, chloroform, acetonitrile and the like are preferably used. The molar ratio of the raw materials charged in the reaction is not particularly limited, but considering the increase of by-products and economic efficiency, 1 to 2 mol of trichlorosilane or dichlorosilane and 1 mol of chlorosilane are used for 1 mol of the Schiff base. Acetyl chloride is preferably used in a proportion of 1 to 1.2 mol.

The reaction temperature in the above reaction is not particularly limited and can be selected in a wide temperature range, but generally it is -20 ° C to 15 ° C.
It may be selected from the range of 0 ° C. Furthermore, the reaction time varies depending on the reaction temperature, but is generally several minutes to several days, for example 5
You can choose between minutes and 10 days.

The order of adding each raw material in the reaction is not particularly limited and may be selected as necessary. Generally, trichlorosilane or dichlorosilane and chloroacetyl chloride may be added to the Schiff base compound at room temperature or under cooling. A Schiff base compound may be added to a solution of trichlorosilane or dichlorosilane and chloroacetyl chloride. In these cases, in general, a solvent is often used, and a Schiff base compound, trichlorosilane or dichlorosilane, and three components of chloroacetyl chloride may be added and reacted in the solvent, and each component is dissolved in the solvent. Alternatively, each of these solvents may be added and reacted.

The method for purifying the amide compound obtained by the above reaction is not particularly limited. Generally, after completion of the reaction, atmospheric pressure, reduced pressure or vacuum distillation may be carried out, and if necessary, washing, recrystallization or chromatographic purification methods can be used.

The N-substituted-chloroacetamide thus obtained exerts an excellent herbicidal effect on pre-emergence and post-emergence soil treatment or foliar treatment of grass weeds, broad-leaved weeds and perennial weeds. In particular, it shows remarkable herbicidal effect on grass weeds, for example, it shows excellent herbicidal effect not only on germination but also on the grass that grows at 1.5 leaf stage against Nobie, which is a highly damaging weed in paddy fields. . Moreover, it is highly safe for paddy rice not only in seedlings at the 1.5 leaf stage but also during germination.

Furthermore, since the N-substituted-chloroacetamide has a high degree of selectivity between Nobie and paddy rice, the N-substituted-chloroacetamide can be applied at a long growth stage from the germination stage to the growth stage of paddy rice. It has an excellent advantage that the suitable period is significantly longer than that of conventional herbicides. Further, the advantage that it can be applied to flooded direct-seeded rice very safely is a major feature of the N-substituted-chloroacetamide.

Furthermore, since it exerts a selective herbicidal effect when it is used as a herbicide for upland fields, it can be applied not only to the broad-leaved action of soybeans, cotton, corn, etc., but also to rice crops such as wheat, barley, corn and upland rice without damage. can do.

In order to describe the present invention more specifically, examples and reference examples will be described below, but the present invention is not limited to these examples.

Example 1 A flask was charged with 5-chloro-2thienyl isopropyl ketone (6.82 g, 0.0028 mol) and ethyl orthoformate (4.77 g, 0.032 mol) and placed on an oil bath (105 ° C). The resulting alcohol was heated and stirred for 4 hours. After cooling, the reaction solution was distilled to obtain a pale yellow liquid (4.16 g). Boiling point is 83 ℃ /
It was 0.4 mmHg.

The infrared absorption spectrum of the compound was measured and found to be 30
Absorption based on CH at 60-2850 cm ^-1 , 1650 cm
^-1 to , And strong absorption based on -N = CH- at 1625 cm ^-1 .

Moreover, when the mass spectrum was measured, it was found to be m / e244.
Molecular ion peak (M ), M to m / e 215 -C_TwoH₅Peak corresponding to, m / e199 to M -OC_TwoH₅Peak corresponding to, at m / e 172The peaks corresponding to are shown.¹ H-nuclear magnetic resonance spectrum [tetramethylsilane group
Quasi, σ (ppm)] was measured. The analysis result is as follows
Met.

(a) 6.15 (d, 1H) (b) 6.40 (d, 1H) (c) 1.85 (d, 6H) (d) 7.23 (s, 1H) (e) 4.18 (G, 2H) (f) 1.32 (t, 3H) The elemental analysis values are C54.08%, H5.81%, N
5.86%, the composition formula C ₁₁ H ₁₄ NOClS (2
43.76) calculated C54.20%, H5.7
9% and N was 5.75%.

From the above results, it became clear that the isolated product was N-ethoxymethylidene 1- (5-chloro-2-thienyl) -2,2-dimethyl-ethenylamine. The yield was 61%. The No. of the compound is 1.

Example 2 Various Schiff base compounds were synthesized in the same manner as in Example 1. Table 1 shows the No., structure, and elemental analysis values of the synthesized compounds. In addition, R ₁ , R ₂ , R ₃ in the table,
R ₄ , Is R ₁ , R ₂ , R ₃ , R ₄ in the following formula, It corresponds to.

Reference Example 1 N-ethoxymethylidene 1- (5-chloro-2-thienyl) -2,2, dimethyl-ethenylamine (2.44) obtained in Example 1 was placed in a three-necked flask equipped with a dropping funnel.
g, 0.010 mol) and benzene (15 ml) were added, and while stirring under ice cooling, chloroacetyl chloride (1.20 g, 0.011 mol) and trichlorosilane (1.80 g, 0.013) were added from a dropping funnel. Mol of benzene (5
ml) solution was added dropwise. After the dropping was completed, the temperature was returned to room temperature and the mixture was stirred at room temperature for 2 hours. After the reaction was completed, an aqueous potassium carbonate solution was added to the reaction solution for neutralization, and the organic layer was extracted with ether.
The extract was dried over sodium sulfate, and the viscous liquid obtained by removing the solvent was purified using a column chromatograph (silica gel; benzene / acetone = 30/1) to give a colorless viscous liquid (1. 72 g) was obtained. Yield 63
%Met. Elemental analysis was performed by a conventional method. This compound is shown in Table 2 as Compound No. 113.

Reference Example 2 By the same method as in Reference Example 1, various chloroacetamide compounds were synthesized. No., structure of synthesized compound,
The silane compounds used, the elemental analysis values and the yields are shown in Table 2. In the table, R ₁ , R ₂ , R ₃ , R ₄ , Is R ₁ , R ₂ , R ₃ , R ₄ in the following formula, It corresponds to.

Formulation Example 1 (wettable powder) N- [1- (5-chloro-2-) obtained in Reference Example 1
Thienyl) -2,2-dimethyl-ethenyl] -N-chloroaceto-ethoxymethylamide (Compound No. 113)
10 copies, Sieglite (Product name: Sieglite 禦
85 parts of a 2: 1 mixture of Kunilite (trade name: manufactured by Kunimine Industry) and 5 parts of Solpol 800A (trade name: manufactured by Toho Chemical Industry) as a surfactant are uniformly mixed and pulverized to 10%.
A wettable powder was obtained.

Reference Example 3 A rice pot (variety: Akinishiki) at the 3-leaf stage after seeding with paddy field weeds was filled with paddy soil (alluvial loam soil), which was stirred by adding water to a porcelain pot of 1/8850 are, to a depth of 1 cm. After transplanting, water was added to make a 3 cm submerged state. Preparation Example 1
A water-diluted solution of a wettable powder of each compound prepared according to 1. was added dropwise at a predetermined amount at the time of germination of weeds. Table 3 shows the results of investigation of the herbicidal effect of each test compound after 3 weeks of growth after being treated at an average temperature of 25 ° C. However, the broad leaves shown in the table refer to the genus Adena, the scabbard, the red pepper, and the like. In addition, evaluation is made into 6 steps, and in the numbers in the table, 0 indicates normal, 1 to 4 indicate an intermediate between normal and complete death, and 5 indicates complete death.

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Claims (1)

[Claims] 1. A general formula (In the formula, R ₁ represents a substituted or unsubstituted heteroaryl group, R ₂ and R ₃ represent the same or different hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ₂ and R ₃ And may be linked to each other to form a cyclic alkylene group, R ₄ is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, or a substituted or unsubstituted aryl. represents a group, R ₅ represents a hydrogen atom, or an alkyl group having 1 to 6 carbon atoms, X represents an oxygen atom or a sulfur atom, n represents 0
Or represents 1. However, when R ₅ is a hydrogen atom, n is 0.
Is. ) A Schiff base compound represented by.